1. Field of the Invention
The present invention generally relates to a method and apparatus for automatically reformatting the pattern of a beam from a light source to prevent it from illuminating certain areas in the vicinity of a light forward of it; more specifically, to a headlight with an output comprising a multiplicity of microbeams projecting a composite beam of light in the forward direction, whereby the direction of an incoming beam of light impinging on the forward projecting headlight will be sensed by sensors controlling the individual microbeams to darken those microbeams that would otherwise illuminate areas near to the source of the impinging beam, thus eliminating the blinding of a driver in an oncoming vehicle, while continuing to provide intense forward illumination.
2. Description of the Prior Art
One of the problems exhibited by existing headlights lies in the fact that the headlight operates in only one of two modes, either as a "high beam" or as a "low beam." A driver on an open road who sees no oncoming vehicles' headlights or preceding vehicles' taillights will usually operate the headlights on the high beam setting. As another vehicle is overtaken or is approaching, the driver will switch the headlights to the low position. This is required by law, as well as by common courtesy and good sense, to reduce the possibility that other drivers will be dazzled by the light. There have been automatic systems to relieve the driver of the task of switching the modes. In cities, and on busy rural roads, the driver may never be able to switch to high beams, and, thus, will be driving with a handicap at all times.
There are numerous potential problems with the arrangement described above. First, the driver may fail to switch to low beams through neglect, absent-mindedness, or caprice. This causes the drivers ahead, whether they are leading the car being described or are approaching, to be dazzled. Second, even if the driver does switch his lights to low beam, the drivers forward of him may still be dazzled on occasion. Some of those who are especially sensitive may find that the light from even properly operating low beams causes them discomfort and reduces their ability to see at night. Glare is a particular problem with certain classes of drivers; e.g., the elderly. Third, when a car is not level, as when it is overloaded in the rear or when it is cresting a hill, the central rays of the beams of its headlights are raised or lowered with respect to the road's surface and may cause glare even to a driver with normal vision. Fourth, headlights on automobiles frequently are misaligned either because of a slight jar or bump, or simply because vibrations of the vehicle shift their adjustments.
From the driver's perspective, the low beam's illumination is often so dim that it is difficult to see street signs, terrain features, obstructions or potholes in the road, even pedestrians, bicyclists or animals. Yet under many circumstances, it is impossible to use the high beams, even momentarily, without causing problems to other motorists.
Attempts to solve these problems have fallen into several categories: Systems that sense oncoming headlights and cause the automobile with the system to switch to the low beam mode; systems which attempt to control the intensity profile of the beam by using a reflector or lens shaped to control the output beam in some predetermined way; systems to move the headlamps in response to changes that occur to the automobile on which they are mounted; e.g., a tilt sensor used to determine whether loading causes the headlights to point skyward controlling a servo to change the elevation angle of the lamps, movement of headlight beams in response to changes in the vehicle's steering mechanism, etc.; and systems which employ polarizers in the headlight and a cross polarizer in the windshield.
However, these heretofore known devices have exhibited the following problems and shortcomings:
(a) Automatic headlight dimming devices are well known in the art. For example, the device described in U.S. Pat. No. 5,329,206 addresses the issue of driver forgetfulness or inattention, but fails to deal with the other problems listed above. PA1 (b) Controlling of the shape and direction of the headlight beams is generally taught in U.S. Pat. Nos. 5,065,288; 5,171,082; and 5,469,340; but all are passive devices which shape the beam(s) in a predetermined profile that is expected to cause the fewest problems to the oncoming drivers under a variety of circumstances. This is a compromise, at best, between reducing glare and providing enough light to the driver for adequate visibility. Moreover, under many conditions, the driver ahead is not in the area of reduced light intensity, such as when on an uneven surface, when the driver fails to lower the beams, or when there is a misalignment of the headlamps mounted on the car. PA1 (c) Still another apparatus that steers the overall beam downward or upward is described in U.S. Pat. No. 5,331,251 whereby the elevation angle of the headlights is changed in response to variations in vehicle attitude. This is accomplished by sensing its headlight reflections from the road. Even though it can sometimes compensate for changes in loading, spring sag, and the like, depending on the positions of the sensed portions of the roadway, it may not correctly sense the change in effective beam position that occurs when cresting a rise on a wavy road. In fact, examination of the mode of operation suggests that, in some cases, it may even exacerbate the problem for the oncoming driver. PA1 (d) A polarization approach has been advanced as a solution to at least some of the described problems, which requires the driver to wear polarized spectacles or to have a polarized windshield. This will reduce the intensity of the visual clues one receives from ambient light along with the reduction in headlight glare. Implementation would require that all vehicles and/or drivers be equipped with some type of polarizing means, which would be highly impractical.